Online publishers often include third party content on their web pages. These third parties provide services that include, but are not limited to: analytics, advertising, widgets that add functionality for end users, and behavioral tracking. These third party services typically are provided at least in part by embedding onto a first party publisher's web pages a snippet of third party HTML and JavaScript code.
This HTML and JavaScript code, once executed, performs the functionality that the publisher originally intended, but may also bring in requests, such as data collection requests, that were not authorized by the publisher, such as requests by and/or on behalf of unwanted third parties. These data collection requests can be in the form of images (most common), scripts, or iframes—theoretically any tag that creates an HTTP transaction. As an example, and without limitation, a first party publisher's web page (for example, an Autos site that is used by consumers to compare car prices) may include the follow HTML code from an authorized third party, in this case one associated with the fictional domain “3rdparty.com”:                <script src=“http://3rdparty.com/writePixel.js”></script>        
However, writePixel.js in the above example may contain something like the following:                document.write(‘<img src=“http://blacklisted.com/?make=bmw&model=5-series&price=50000-70000”/>’);        
In the above example, an authorized third party (“3rdparty”) has included on the publisher's page a tag that results in a call not authorized by the publisher being made out to a site associated with an unauthorized third party (“blacklisted”), which in this example results in user data being passed to the unauthorized third party, for example cookie data stored on the user's computer. Using the data that is passed along with the unauthorized call, the third party (“blacklisted.com”) is now able to track that user as one being in-market for high-end luxury cars.
These unwanted requests may have unwanted affects, such as:                Devaluing the publishers online advertising inventory by making their audience's data available to channels not controlled by the publisher, ultimately decreasing revenue for the publisher.        Increasing web page load time for end users with additional HTTP traffic. In addition to creating a poorer experience for end users, this leads to lower revenue for the publisher when end-users abandon sites or visit fewer pages because the web pages are slow.        Compromising the privacy of the users by having their data shared with unauthorized companies. With an evolving privacy regime, unwarranted distribution of user's data is a big concern for Publishers.        